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A Study on the Behaviour of RC Beams Retrofitted Using CFRP Laminates Under Single Point Loading

P. L. Karuppiah, R. Angeline Prabhavathy and R. Anantha Babu

The technique of strengthening of reinforced concrete beam with externally bonded CFRP has been successfully applied in Civil Engineering. This paper discusses the effect of shear and flexural strengthening of RC beams on the stress distribution, initial crack, crack propagation and ultimate strength. The experimental programme includes testing of five reinforced concrete beams of which three beam specimens are casted with bonding CFRP and the remaining two beams without CFRP which is considered as the control beam and the retrofitted beam. The CFRP epoxy bonded specimens are Semiwrapped beam (ASW-F), U wrapped beam (AUW-U) and beam wrapped in the flexural zone (AFW-D). The specimens are casted with M20 design mix. The deflection, ultimate load, cracking, shear and flexural failure for rectangular beams bonded with CFRP are investigated. The general and regional behaviour of concrete beams with bonded CFRP are studied with the help of strain gauges. The appearance of the first crack and the crack propagation in the structure up to failure are also monitored. It is concluded that in beams bonded with Semi wrapped (ASW-F) and U-wrapped (AUW-U), there is a delay in the formation of initial crack and the ductility ratio is more, which is desirable in earthquake prone areas.